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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 749 · 40 sums
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The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.

NameDateTime takenScore ___ / 40
  1. 1.If a − b = 3 and ab = 108, what is a² + b²?
  2. 2.Use (a − b)² = a² − 2ab + b² to find 65².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 21².
  4. 4.If a + b = 12 and ab = 27, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 98² − 87².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 49².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 46².
  8. 8.Use a² − b² = (a + b)(a − b) to find 55² − 13².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 91².
  10. 10.If a + b = 3 and ab = 2, what is a² + b²?
  11. 11.Find the value of x² − 2xy + y² when x = 12 and y = 7.
  12. 12.If a + b = 10 and ab = 21, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 47² − 19².
  14. 14.Use a² − b² = (a + b)(a − b) to find 37² − 27².
  15. 15.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 36².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 62².
  18. 18.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  19. 19.Use a² − b² = (a + b)(a − b) to find 24² − 13².
  20. 20.Find the value of x² + 2xy + y² when x = 15 and y = 4.
  21. 21.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  22. 22.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 45².
  24. 24.If a + b = 5 and ab = 6, what is a² + b²?
  25. 25.Find the value of x² + 2xy + y² when x = 13 and y = 9.
  26. 26.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  27. 27.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 39².
  29. 29.Find the value of x² − y² when x = 11 and y = 3.
  30. 30.If a − b = 1 and ab = 42, what is a² + b²?
  31. 31.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  32. 32.Find the value of x² − y² when x = 4 and y = 2.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 107².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 43².
  35. 35.Find the value of x² − y² when x = 14 and y = 5.
  36. 36.Find the value of x² − 2xy + y² when x = 8 and y = 3.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 74².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 102².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 15².
  40. 40.Find the value of x² + 2xy + y² when x = 14 and y = 2.

Answer key

  1. 225
  2. 4225
  3. 441
  4. 90
  5. 2035
  6. 2401
  7. 2116
  8. 2856
  9. 8281
  10. 5
  11. 25
  12. 58
  13. 1848
  14. 640
  15. 144
  16. 1296
  17. 3844
  18. 4884
  19. 407
  20. 361
  21. 399
  22. 364
  23. 2025
  24. 13
  25. 484
  26. 3551
  27. 100
  28. 1521
  29. 112
  30. 85
  31. 4875
  32. 12
  33. 11449
  34. 1849
  35. 171
  36. 25
  37. 5476
  38. 10404
  39. 225
  40. 256

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